Water Quality Effect of Pollutants on Algal Growth-paper代写

留学生paper代写精选范文：“Water Quality Effect of Pollutants on Algal Growth”，这篇论文讨论了水质污染物对藻生长的影响。近几年虽然工业的发展非常快，但带来的水污染问题也越来越严重，而水污染中的氮磷等元素对藻类的生长有着非常大的影响。针对这种情况，文中做了一个实验，分别测试了不同浓度的氮、磷和酸雨对于藻类生长的影响。

Abstract:

With the development of the industrialization, our environment has been polluted and the condition is getting worse. Water pollution is one part of the environment pollution, water quality has a great influence on the life of the living beings. The main purpose of our experiment is to study the effects of different pollutantson algal growth.

In this experiment, nitrogen, phosphorous and acid rain are the main research elements. Nitrogen and phosphorus is the basic element of algae growth. So nitrogen and phosphorus must have effect on algal growth. Expect from that, acid rain also can influence the growth of algal. Because acid rain can change the PH of water, destroy the algal growth environment. Spectrometer is used to measure the change of algal.

According to the experimental result, all of the nitrogen, phosphorous and acid rain can increase the growth of algal. Among these three elements, phosphorous has the biggest effect on algal growth. In addition to this, different concentration has different influence.

Introduction:

Due to human activity, a lot of nitrogen and phosphorus elements are discharged into rivers and lakes, which leads to algal blooms. Then, the speed of organic producing is far more than consumption, organics begin to accumulate. It will destroy the aquatic ecological balance. Several studies have shown that phytoplankton is the first to be affected by the water pollution.“Algae respond rapidly and predictably to a wide range of pollutants and, thus, provide potentially useful early warning signals of deteriorating conditions and the possible causes (McCormick and Cairns, 1994).”Therefore, algal is used as experimental material.

In order to understand how different pollutants effect algal growth, we need to know the knowledge and method of inoculation of algal cultures. Algal growth needs a lot of elements, like carbon, hydrogen, nitrogen, oxygen, phosphorus and sulfur. Amongst these, nitrogen and phosphorous nutrients are the key elements to the growth of algal. Algal culture needs a lot of conditions, like suitable illumination, humidity, PH and temperature. These conditions will remain the same in the control experiment. Algal growth needs suitable culture medium, which contains adequate nutrition elements. Besides, the culture medium needs to strict sterilization. Asepsis operation can effectively reduce experiment errors.

What is the concrete influence? And how does it affect? That is what we need to summarize after the experiment. In this experiment we use same volume but different liquid which have different pollution elements to grow algal. And, distilled water is used to serve as control. We use this tube to represent the normal rate of algal growth. We use vinegar to simulated acid rain. And inthis experiment use express the effects of different pollutants on algal growth according to the rate of algal growth. At the same time, we also can differentiate the degree of influence. In the process of experiment, we should observe the experiment phenomenon in detail, and write down relevant data.

Materials:

Before the experiment we need to prepare:(1). Seven 25 mL test tubes for different liquids. (2). One graduated cylinder to measure the liquid volume. (3). Some algal (4). Nitrogen, phosphorus elements andvinegar. Which are used to dissolve into various liquids. These liquids are control (C), low phosphorous (LP), high phosphorous (HP), low nitrogen (LN), high nitrogen (HN), low acid rain (LAR), and high acid rain (HAR).Each solution prepare in four pieces. (5). Distilled water. (6). Spectrometer, which is used to measure the change of algal. (7). Cotton ball and gauze. (8). Tissue.

Methods:

Firstly, prepare different solution. Low concentration solution. Add 2.5 mL of algal, 1.5 mL of the pollutant, and 11 mL of water into three tubes. Pollutants are nitrogen, phosphorus and vinegar. Then, prepare high concentration solution. Add 2.5 mL of algal, 3 mL of pollutant, and 9.5 mL of water into another three tubes. As for control group. Use 2.5 mL of algal, o mL pollutants, and 12.5 mL of water.

Secondly, use a plug with a small piece of cotton and a small square piece of gauze measuring about 5 x 5 cm to tightly close tubes. According to the instructor, put the tubes into the suitable area. Then, place the plant growth lamp into the right area. This experiment lasts two weeks.

Two weeks later, we need to use spectrometer, cuvettes, test tubes, distilled water, and a tissue wipe. Measure the absorbance of tube with distilled water. Record the data, then we will use the data as the zero.Fill a cuvette with distilled water. Dry the outer wall of the test cuvette. Put the cuvette in the spectrometer and carefully adjust the wavelength to 450nm.Read the absorbance of the distilled water using the absorbance scale. Recalibrate the spectrometer to 0.

Thirdly, mix the liquids in the seven tubes by putting the tubes on the table in a 10 cm circle and swirling about 10 seconds. Then, pick one of the tube in order, put the inside liquid into a clean cuvette until three-quarters. Wipe the cuvette's exterior with a tissue wipe. Put the cuvette in the spectrometer. Read the accurate absorbance value. Record the value.

Repeat steps in the test tubes order, and write down the data in turn. In order to reduce the experimental error, each group of experiment repeats four times. Then, organize the data into table 1.In the meanwhile, put the data into computer, transparency or blackboard.

Finally, clean the experiment equipment, properly handle the laboratory reagents, wipe all the tubes. Put back the experiment apparatus on the right place. Finish experimental data, analyze the results of the experiment.

Results:

The result shows that the all the three pollutant elements in the water will promote the growth of algal. And different concentration has different degree of influence. Different pollutant elements have different influence. Among all the pollutant elements, phosphorus has the biggest effect on algal growth.

The experiment adopts the method of controlled experiment, so we can easily find the change through the contrast. The control group has played an important role in the experiment.

Table 1:Absorbance (at 450 nm)

Lab croup     Control   Low Nitrogen       High Nitrogen      Low Phosphorous       High Phosphorous      Low Acid Rain       High Acid Rain

1     0.113     0.222     0.222     0.22       0.356     0.147     0.057

2     0.141     0.154     0.164     0.264     0.246     0.171     0.138

3     0.085     0.135     0.2  0.288     0.218     0.146     0.3

4     0.003     0.026     0.062     0.028     0.19       0.05       0.049

Mean:    0.0855   0.13475 0.162     0.2  0.2525   0.1285   0.136

This experiment judge the algal growth by the different values of absorbance. According to the sheet, we find no matter the concentration of pollutants is low or high, it promotes the growth of algal. And different concentrations have different effects. In general, high concentration liquids have a great impact for the growth of algal. But, that is inaccurate. We find that even in the same condition with high acid rain, the results vary widely. So algal have most appropriate growth environment.

Discussion:

We all know that eutrophication will lead to algal pollution, so we suppose that pollutants will promote the growth of algal before the experiment. Obviously, the results of the experiment fit the hypothesis. Phytoplankton is the first to be affected by the water pollution. In fact, “algae under the condition of different nitrogen and phosphorus ratio, optimal growth conditions for nitrogen and phosphorus ratio equals 40 : 1, algae growth depends on the quality of the nitrogen concentration (Komatsu,Fukushima and Shiraishi, 2006).”

There is another hypothesis. Acid rain does harm to the growth of algal. “Algal growth can change environment PH, Acid rain can change the PH of the water. The multiply of algal can rise the PH (Feng, Wu and Feng, 2008).” To the contrary, acid rain contains hydrogen ion, it may neutralize bicarbonate ion to form weak acid carbonate in the water. When the hydrogen ion was worked out, the new hydrogen ion will reduce the PH. “Algal growth has suitable PH range, through the experiment, the most suitable range for algal growth is between 8.5 and 9.5(Feng, Wu and Feng, 2008).” In some ways, acid rain is not conducive to the growth of algal. So we found it was not accurate, the experiment can still be improved.

In order to have an impeccable experiment and get accurate experimental data, we can improve the experiment in the following aspects.

Firstly, we can subdivide the concentration of different pollutants, not just roughly divide pollutants into low or high concentration. After the subdivide groups, we can have a clear understanding of the experiment phenomenon. For example, in this experiment, both low and high nitrogen can promote the growth of algal, but the influence degree is different. Subdivide groups can reflect concrete results. Moreover, we can find the most suitable concentration of algal growth.

Secondly, reduce experimental errors as far as possible. The experiment error is inevitable in every experiment, but we can reduce the errors by improving the experimental methods. This experiment just repeats four times, that is never enough. Repeat experiment can make the experimental data fitting to an approximation. Compared with the value in the other groups can eliminate the error value, making the experimental data more accurate.

Thirdly, increase the pollutant elements. The contaminated water not only has excess nitrogen and phosphorus elements. There are also many heavy metal elements in the water, likecopper, iron, zinc, and others. Heavy metals also have effect on algal growth. “Heavy metals directly affect the photosynthetic machinery by binding to the various sensitive sites of the photosynthetic apparatus (Kale, 2014).”So increase the experimental group can get a more comprehensive conclusion of the experiment.

Finally, extend the time of the experiment. We limit this experiment time in two weeks. After two weeks, we observe the experiment phenomenon and summarize conclusions. But we don’t know whether it is the final result. Maybe the experiment result is not stable. For instance, the growth rate may be fall if we continue to observe for a period of time. So extend the time until the result is nearly stable.

Eutrophication of lacks and rivers is one of the most serious water pollution problems. Eventually ecosystem structure and function are damaged. Eutrophication is divided to eutrophication of natural water and man-made eutrophication. But the former needs a long term for thousands of years. Man-made eutrophication can change the water quality just use few years. Eutrophication leads to algal blooms. Algal consume a large amount of oxygen in the water, water quality decline, killing a lot of fish and other aquatic life, which then decay and release. This is a vicious circle. As for the acid rain, it has more serious harm. For example, acid rain not only changes the PH of rivers, lakes and soil, but also corrodes bridges and buildings, let along to human. Acid rain belongs to air pollution, but when the acid rain flow into rivers, it will compromise water quality.

Studying the effects of pollutants on algal growth is just a basis, our ultimate aim is to reduce the pollution of the environment. We know pollutants can influence the growth of algal and what the effect is. That will provide some theoretical basis to water pollution control.

Reference List:

1. Feng, M., Wu, Y., & Feng, S. (2008). Effect of different n/p ratios on algal growth. Ecology & Environment.

2. Mccormick, P. V., & Jr, J. C. (1994). Algae as indicators of environmental change. Journal of Applied Phycology, 6(5-6), 509-526.

3. Komatsu, E., Fukushima, T., & Shiraishi, H. (2006). Modeling of p-dynamics and algal growth in a stratified reservoir—mechanisms of p-cycle in water and interaction between overlying water and sediment.Ecological Modelling, 197(3), 331–349.

4. Kale, S. R. (2014). Effect of heavy metal on aquatic algae and influence of vermiwash on algal growth. Golden Research Thoughts, 3(11), 1-3.

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